Return mapped ports when requesting runners

We now store the mapped ports returned by Nomad locally in our runner
struct and return them when requesting the runner. The returned ip
address is in most Nomad setups not reachable from external users.

nomad/api_querier.go

@@ -40,6 +40,9 @@ type apiQuerier interface {
 	// job returns the job of the given jobID.
 	job(jobID string) (job *nomadApi.Job, err error)
 
+	// allocation returns the first allocation of the given job.
+	allocation(jobID string) (*nomadApi.Allocation, error)
+
 	// RegisterNomadJob registers a job with Nomad.
 	// It returns the evaluation ID that can be used when listening to the Nomad event stream.
 	RegisterNomadJob(job *nomadApi.Job) (string, error)
@@ -193,3 +196,18 @@ func (nc *nomadAPIClient) job(jobID string) (job *nomadApi.Job, err error) {
 	job, _, err = nc.client.Jobs().Info(jobID, nil)
 	return
 }
+
+func (nc *nomadAPIClient) allocation(jobID string) (alloc *nomadApi.Allocation, err error) {
+	allocs, _, err := nc.client.Jobs().Allocations(jobID, false, nil)
+	if err != nil {
+		return nil, fmt.Errorf("error requesting Nomad job allocations: %w", err)
+	}
+	if len(allocs) == 0 {
+		return nil, ErrorNoAllocationFound
+	}
+	alloc, _, err = nc.client.Allocations().Info(allocs[0].ID, nil)
+	if err != nil {
+		return nil, fmt.Errorf("error requesting Nomad allocation info: %w", err)
+	}
+	return alloc, nil
+}